Apparatus for producing anhydrous magnesium chloride



Dec. 17, 1935. w. MOSCIjEL 2,024,242

I APPARATUS FOR PRODUCING ANHYI JROUS MAGNESIUM CHLORIDE Original Filed June 17, 1930 f1 52E; :lgf: & 3 I:

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I f 7% 1 2 z a T III: 7a 1 d In venfor Patented Dec. 17-, 1935 APPARATUS FOR PRODUCING ANHYDROU MAGNESIUM CHLORIDE Wilhelm Moschel, Bitterield, Germany, asslgnor,

by mesne assignments, to Magnesium'Development Corporation, a corporation of Delaware Original application June 17, 1930, Serial No;

461,724. Divided and this application November 23, 1934, Serial No. 754,479.

June 20, 1929 In Germany 3 Claims. (Cl. 204-19) 4 This invention relates to apparatus for the de- M gCla and 1.8 percen of 80- The relatively hydration of hydrated.magnesium chloride and the-subsequent-electrolysis of the anhydrous magnesium chloride formed therein, and is a division- 5 al application of my-copending application Serial No. 461,724, filed June 17, 1930 and bearing the title fProcess of producing anhydrous magnesium chloride.

It has. generally been recognized as essential in the production of magnesium from magnesium chloride by electrolysis of a fused electrolyte that the magnesium chloride consumed in theprocess should be replaced by magnesium chloride which is dehydrated as thoroughly as possible. On the other hand, it is well known to all those skilled in the art that the complete dehydration of the hydrates of magnesium chloride by treating them in a current of desiccated hydrochlorid acid this being the only process hitherto feasible on a technical scale-oifers great technical difilculties and is very expensive. An object of the present invention, therefore, is to employ such hydrates of magnesium chloride which are comparatively easily produceable, particularly the hydrate cell and to effect complete electrolytic cell itself.

According to the present invention the hydrate to be treated is introduced into a fused mixture of chlorides, for example a mixture consisting of s Per cent Potassium chloride 50 Sodium chloride 40 Magnesium chloride Example.

MgClz.2HzO, directly for feeding the electrolytic dehydration in the- Into 500 kgs. of a' fused mixture of chlorides having a temperature of about 700 C. and containing besides alkali chlorides 12.6 percent of MgClz and 1 percent of MgO, 135 kgs. of magnesium chloride di-hydrate consisting of 65.5 percent of MgClz, 3.9 percent of MgO, balance r water. are gradually introduced. The melt is stirred for some time until the evolution of water vapours has ceased. 593 kgs. of an anhydrous melt are thus obtained containing 25.5 percent small increase of the magnesium oxide contents is largely due tothe small amounts. oi. magnesium oxide contained in the' di-hydrate salt as an impurity and introduced along therewith.

I have further found that it is possible to feed h r a bath in which electrolytic decomposition of a melt containing anhydrous magnesium chloride is carried outdirectly' with'the di-hydrate salt provided the aforesaid conditions are constantly 10 maintained, since the .limits' of concentration specified in the foregoing-example are entirely sufilcient for carrying on the electrolysis. Ac-- cording to the present invention, a portion of the electrolyte impoverished in MgClz is passed into 15 a separate chamber, preferably forming-a subdivision of the electrolytic cell and separated from its main portion by a suitable partition. Into this chamber the xii-hydrate is introduced,"

preferably in a preheated condition, at such a 20 rate that the MgCh content in the fused product does not exceed 50 percent. Dehydration takes place quite smoothly in the chamber and without any perceptible decompositioncof the magnesium.

chloride. The electrolyte thus replenished with 26' tions or the device, the broken lines in Figure 1 and their respective numbers indicating the planes in which the different sections are taken. In a trough-shaped container a provided with a lining b of ceramic material, an anode e con-- sisting of two plates of graphite and the iron cathode j are inserted so as to enter into the electrolyte consisting of 50 percent of NaCl, 35 r percent of KCl and 15 percent of MgCla. The

container is spanned by a partition 0 of chamotte which vertically extends just below the level of the, electrolyte and divides the cell proper into an anodic chamber 0 serving for the recovery of chlorine and a cathodic chamber d in which the metal is collected. There are further provided chambers h and i separated from the main cell d by partitions k and l of ceramic material. In partition k (ct. Figure 3) extending down to the bottom of the container there is provided a narrow channel s through which, owing to the buoyancy .of the chlorine-ascending in the anode 56' chamber, some of the electrolyte is caused to en- -ter into the chamber h. Into this chamber also the (ii-hydrate at the rate required by the invention is introduced and immediately gives oiT its water content by evaporation, whereupon the electrolyte replenished with regard to its magnesium chloride content enters chamber i through a gap provided below partition I, and hence fiows back into the main chamber. circulation of the electrolyte in the manner described is sumcient for maintaining thenecessary temperature in chambers h and i. However, it

is also possible to individually heat these chambers in any known manner, for instance, by means of an alternating current. g

The present invention is not limited to the dehydration of the di-hydrate MgCI2.2H2O, as other hydrates, such as the tetra-hydratexMgClzAI-IaO, may also be treated in a similar manner. However, the dehydration of other hydrates to a point corresponding to the di-hydrate when carried out in the usual manner, for example, in a reverberatory furnace, oflers no difliculties. I

therefore preferably employ the di-hydrate as the starting material in my process.

Another form of carrying out the present invention consists in supplying the magnesium chloride to the electrolyte by introducing the hydrates in an entirely separate container into the tially vertical partition adapted to be only slightly immersed below the level of the electrolyte within said container and extending substantially at right angles to the first of said partitions so The continuous as to provide an anode chamber and a cathode chamber in one of the said compartments, an anode and a'cathode in their respective chambers, means for passing a portion of the electrolyte contained in the first of said compartments into 5 the other compartment, and means for returning the electrolyte into the first of said compartments.

2 An electrolytic cell comprising an electrolyte container, a substantially vertical partition extending down to the bottom of said container so as to form two substantially separate compartments within said container, another substantiallyvertical partition adapted to be only slightly immersed below the level of the electrolyte within said container and extending substantially at right angles to the first of said partitions so as to provide an anode chamber and a cathode chamber in one of the said compartments, an anode and a cathode in their respective chambers, a plurality of openings located in the first of said partitions and connecting the said compartments with each otherin such a ,-manner as to enable a circulating flow of the fused electrolyte between said compartments by virtue of the electrolytic action.

3. An electrolytic cell comprising an electrolyte container, a substantially vertical partition extending down to the'bottom of said containerso as to form two substantially separate compartments within said container, another substantially vertical partition adapted to be only slightly ,immersed below the level of the electrolyte within said container and extending substantially at right angles to the first of said partitions so as to provide an anode chamber and a cathode chamber in one of the said com-.

' partments, an anode and a cathode in their respective chambers a narrow channel located in the upper part of said other partition and con- 40 necting the anode chamber with said other compartment, and a gap located below said other partition and connecting the cathode chamber with said other compartment.

WILHELM MOSCHEL. 

